From owner-svn-src-head@freebsd.org Mon Jul 4 20:09:21 2016 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 24BD6B9144B; Mon, 4 Jul 2016 20:09:21 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-io0-x22c.google.com (mail-io0-x22c.google.com [IPv6:2607:f8b0:4001:c06::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DCB68294B; Mon, 4 Jul 2016 20:09:20 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: by mail-io0-x22c.google.com with SMTP id s63so158653940ioi.3; Mon, 04 Jul 2016 13:09:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=lxPyjXmtF8+2Bp6BRrmY+z+Y4ooZo7Dqli9cpEUhLFc=; b=tiqz+T3bK23eHe+yfbUO41pccEmbH2S1hponnMbzTYUrLofZdo48cmlCMXjBa/4GBK CiixkyzyjRfpF2MrUC8Zzxjmqv/k8CJDFS/TzpN1nF+G148OpTrG1oNKtU9gk2mQTiqv wdKPRLOVyCATrTinxUrHLdE+00gB0pCMNd6kRzcvCCCBbx3vOvLgpfQ9sBEQRdyoKJ/b IH+1JpnL3QlQCrcg+GJa3FqQMjbWdBPl7t/0GalzfOIdxgJfY2VnCDD1/fmRcMK6bOzg L80bwekE5/RmweTdZBUWeI4N69S3CCSifrXh4H7ZXGxek2ld4uN2TwzF+ZuoY6qG6RNV sWIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=lxPyjXmtF8+2Bp6BRrmY+z+Y4ooZo7Dqli9cpEUhLFc=; b=YrsW3cM6+1bFyDWIeBwYtYL7KiSIHLae7O9fi5VU/78ktuDqj1uLjlvqSjdGbv0RVo NxRHGtK2pWNk+kBhLuHLk7NhYvB0xczEimPq3ov9TNsVYaiYHUd0fckzDmHlyApN3P7K /rs0FMOTSL+qWZZSkvK+p6xGmMVVuOPedtG71vD7HjjeINVNa2D236wRFkpwXWSDDx3X 6qsIWrefMzkOAPUHFl2TYZhveES7kHFtnY/xbQBFDzTH8DIwugepvDR1xiuRb8eiLqPv PbTnrMZ12tsaf/t9pWi9rF1YKJO4xTR3YN4QGVZudSZYJYEdP1tPcFALMOXVv8yoUs0A dDSw== X-Gm-Message-State: ALyK8tKd8CT53hh+ODRCNWzUSZRN9W3Ab42v4N/W6CZMGYWacclTbvz+NVcnhNEKtqMdCwgYQ+5AvL8N7ojoyw== X-Received: by 10.107.144.86 with SMTP id s83mr9402195iod.165.1467662960352; Mon, 04 Jul 2016 13:09:20 -0700 (PDT) MIME-Version: 1.0 Received: by 10.36.210.212 with HTTP; Mon, 4 Jul 2016 13:09:19 -0700 (PDT) In-Reply-To: References: <201606281643.u5SGhNsi061606@repo.freebsd.org> <20160629175917.O968@besplex.bde.org> <20160629145443.GG38613@kib.kiev.ua> <20160629153233.GI38613@kib.kiev.ua> <20160630040123.F791@besplex.bde.org> <20160629211953.GK38613@kib.kiev.ua> <20160701005401.Q1084@besplex.bde.org> <20160630180106.GU38613@kib.kiev.ua> <20160701031549.GV38613@kib.kiev.ua> <20160701185743.Q1600@besplex.bde.org> <20160701142516.GW38613@kib.kiev.ua> <20160702153817.O1458@besplex.bde.org> From: Adrian Chadd Date: Mon, 4 Jul 2016 13:09:19 -0700 Message-ID: Subject: Re: svn commit: r302252 - head/sys/kern To: Ed Schouten Cc: Benjamin Kaduk , Bruce Evans , Konstantin Belousov , "svn-src-head@freebsd.org" , "svn-src-all@freebsd.org" , "src-committers@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 04 Jul 2016 20:09:21 -0000 On 4 July 2016 at 12:28, Ed Schouten wrote: > 2016-07-04 21:08 GMT+02:00 Adrian Chadd : >> Does the specification / implementation also mandate that the padding >> is zero'ed out or otherwise initialised? > > Well... That's tricky: > > https://stackoverflow.com/questions/13056364/is-zero-initialization-of-structures-guaranteed-to-wipe-padded-areas > https://gustedt.wordpress.com/2012/10/24/c11-defects-initialization-of-padding/ Right, so if we're not careful, we could leak bits of kernel memory, and it can also screw up key cache comparisons. (I asked this question because I've been screwed by it recentlyish, and it looks like the latest C standard didn't fix it..) -adrian